Inkjet printers function by ejecting small droplets (typically on the order of 1-10 picoliters) of ink in a directed fashion onto media underneath a print head. Contact of the ink droplets onto the paper forms picture elements that collectively constitute a printed image. In general, darker or lighter areas of an image require more or less ink, respectively, per unit area of the paper.
However, the use of water-based inks results in penetration of a large amount of water into the paper, or other print substrate. This creates a need for additional drying in order to enable fast printing speeds, causes undesired deformation of the paper, and places challenges on print quality due to lateral spreading of the ink. Non-aqueous solvents, which can have a much lower latent heat of vaporization than water, are not a viable alternative due to added operating costs and safety concerns arising from the production of large amounts of flammable vapors that also present health risks if inhaled. Slow-evaporating non-aqueous solvents have many of the same issues as with water. Removing a significant fraction of the water content, or other solvent(s), from ink droplets between the time they are produced (e.g., by jetting) and the time they impact the paper would mitigate or avoid these issues.